Nintendo has already confirmed that not every Switch game will support cloud backups. Since no local data backup options exist for the Switch, this means your 100 hour+ save file for Dark Souls Remastered could still be at risk. Switch Online was supposed to be a safety net; pay a monthly or yearly fee and you can copy your data to the cloud should your Switch malfunction or data gets corrupted (it actually happened to us). But this safety net will be yanked if you don't pay your subscription dues.

"We are unable to guarantee that cloud save data will be retained after an extended period of time from when your membership is ended," reads a support page. Nintendo didn't specify how long your subscription has to be inactive before cloud saves are wiped, but I'm guessing it's around 60 days or so, maybe more.

Should your cloud saves be wiped, your NES game save data will also be erased too. Switch Online's classic NES library uses the cloud for saves, but it also use local storage since you can play the games offline. Nintendo says you can re-upload your saves to the cloud if you get another Switch Online subscription.